The Research Of High-voltage Avalanche Diode

In recent years, the application of power semiconductor devices has extended to various fields,and requirements of device reliability become more stringent. High-voltage diode is the basic unitof maintaining stable operation of power devices, the ruggedness of it is very important. The powerdiode may be working in the avalanche breakdown mode in some occasions, the power diodeshould have certain avalanche energy dissipation the avalanche breakdown tolerance. How toimprove the high power diode avalanche breakdown of tolerance is the new research field at homeand abroad of power devices. The purpose of this paper is to improve the tolerance of avalanchebreakdown power diode, to design a high-voltage avalanche diode with2300V.The core idea of this paper is to analyze the avalanche damage mechanism by analyzing theavalanche breakdown characteristics of high-voltage avalanche diode both in theory and simulation,then to conclude the structure with high avalanche breakdown tolerance and make the simulationanalysis and design optimization for the main structure.First, starting from the general high voltage diode structure, with Silvaco-TCAD simulationsoftware to make the simulation and theoretical analysis for the distribution of electric field in thecase of diode reverse breakdown. During high voltage avalanche diode operating in avalanchemode, with the avalanche current increases, the form of the electric field distribution is changed.When the avalanche breakdown current increases to a certain value, nearby nn+junction in thecathode side may appear a secondary electric field spikes, it is the main reason to cause the doubleavalanche and result in the device damage. By introducing a n+buffer layer structure between the n-region and the n+region can control the secondary electric field spikes of nn+junction,consequently increase avalanche breakdown tolerance.Finally, according to the design specifications of the diode with a buffer layer to optimize thedesign. Firstly design the blocking parameter of NPT and PT structure, the base region parametersof a withstand voltage of2300V NPT structure and PT structure are: The NPT structure withND=6.1×1013cm-3and WN=280μm;The PT structure with ND=1.87×1013cm-3and WN=160μm. Byanalyzing the avalanche breakdown tolerance of NPT structure and PT structure, purely see fromthe avalanche breakdown tolerance, the NPT structure more conducive to improve the avalanchetolerance, but considering the importance of the conduction voltage drop in high-voltage field, and choose the PT structure with buffer layer to design the avalanche diode. Balancing avalanchebreakdown tolerance and voltage drop by the consideration of the buffer layer thickness and densityoptimization.Through the Simulation analysis of high-voltage avalanche diode with a buffer layer, bufferlayer can effectively reduce the electric field peak of the cathode side. Delay the emergence ofnegative differential resistance, improving the avalanche breakdown tolerance.